Precision work with nephelometers or turbidimeters is hampered by scattered light along the light path of the instrument caused by interfacial reflections wherever open surfaces exist in the system, such as an air-dielectric boundary. Certain techniques are well known in the optical science to deal with scattered light and background light in general; in particular instances, the techniques include the use of immersion optics, light piping and refractive index matching devices.
One object of this invention is to employ some of these techniques collectively or singly in an improved nephelometer of the type having a multi micro volume specimen well structure equipped with a cover to avoid evaporation and cross contamination of wells.
A very important feature of the invention is the provision on the cover of integral depending immersion light pipes or pins which project into the liquid specimens contained in the micro volume wells and shorter spacer knees on the bottom of the cover which contact the top face of the well structure to establish and maintain a precision length light path.
In addition to these features, the nephelometer employs light pipes and comformable optical couplers to eliminate open optical surfaces or to remove such surfaces to remote locations where the scattering effect is substantially reduced.
Other features and advantages of the invention will appear to those skilled in the art during the course of the following detailed description.